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Abstract.As an initial step of this innovation, in September of 2016, KEPCO (Korea Power Electric Corporation) has launched the world first commercial superconducting cable project, named SSS (Superconducting Smart platform Station in South Korea) project, which will be not only the first commercial trial in the grid but also a test bed for Smart Superconducting Platform in South Korea. The main target design of this project is installation of 23kV 50MVA class HTS cable a system in the power grid. Type of this HTS cable is 3 phases in One Cryostat which is a remarkable way to transfer large power with low voltage and no electric magnetic field that means prevention of heating of other cores of phases and two metal sheaths of the cable. Total length of HTS cable between ShinGal and HeungDuk substations is slightly over 1km and it has 2 sets of normal joint box and 2 sets of termination. In this HTS cable system, a mechanical stress during the cool-down and warm-up is a major issue for increasing stability to set-up the HTS cable system and to connect existing power lines. To solve this issue of SSS project, we developed a simulation program which used Equivalent Solving Method for reducing and predicting thermal contraction force of the HTS cable under the mechanical stress. Also, mechanical strengths of metal sheaths, that made of aluminium material and the former that was stranded of copper wires was measured by the tensile tests. Coefficient of elasticity and thermal expansion according to various temperatures was calculated by the experimental data. And then, the analytical method was applied to verify installation method by approximate 40m length HTS cable that has various installation conditions such as vertical shape, often called snake method, at straight route in installation path. From the above procedures, we find that mechanical strength of each component of the HTS cable can calculate according to installation route in the power grid. IntroductionSuperconducting applications such as a HTS cable, an HTS motor and SFCL for power grid is stateof-the-art technology [1]. Especially, HTS cables can transfer large electrical power source with low losses and are expected to be not only environmental applications but also electromagnetic interference free performance which means no influence adjusting other cables. It has a compact size compared with conventional power apparatus. However, these apparatuses are also considering that are being well-fit and connection of existing applications in the power grid. Thus, various R&D projects were performed and demonstrations were being promoted in the world. Figure 1 shows the case study for the replacement of conventional cable and the installation method of an additional HTS cable in a tunnel in the grid. This way can make more stable power grid and save cost for transferring power source than existing only installation conventional cables because one